Most saws, and especially vertical band saws, have a saw table on which the workpiece or workpiece material is resting. The workpiece is clamped against a fixed clamping element, usually having a vertically extending clamping face, positioned transversely to the feed direction of the saw band. A displaceable clamping jaw, also with a vertical clamping face, is then provided to clamp the workpiece against the fixed jaw. The faces need not be precisely vertical; they may have indentations or grooves, as desired; some clamping devices have clamping jaws which extend at a slight inclination with respect to each other, or in which one clamping jaw has a slight inclination with respect to the other. Since such variations from a vertical position are, however, small, the term used herein and in the claims, "essentially vertical" or "substantially vertical" clamping jaw, will be used for simplicity. The clamping devices usually are in the form of vice jaws, in which a horizontally displaceable clamping jaw is arranged on one side of the cutting plane formed by the saw band for displacement, in clamping direction, over the support surface or table of the saw. Thus, the known clamping devices is suitable for the handling of material as a rule of rod form, which is advanced by sections parallel with and between the clamping faces and is clamped for the individual sawing action.
Vertical band saws are also used for what is called freehand sawing, in which the workpiece is presented on the machine bench to the saw band without the use of the mentioned clamping device. A vice hinders free handling of the workpiece material, and even may make freehand sawing impossible.
During cutting, the workpiece is held only on one side of the cutting plane of the saw band, so that the section being cut off is unsecured and/or unguided. To hold the cut-off section, a further clamping jaw arrangement on the far side of the saw band, or the cutting plane, respectively, is needed.
Miter cuts present problems. For different miter angles, the clamping device must each time be longitudinally--with respect to the workpieces--repositioned in order to be placed as closed as possible to the cutting plane. If such different positioning of the clamping device is not possible, then, having regard to the largest possible miter angle, one must put up with a considerable spacing of the clamping device from the cutting plane, which leads to a correspondingly poor retention of the workpiece material in the cutting region.